The objective of this research program is to determine the effects of perinatal exposure to testosterone or 17 beta estradiol on subsequent tissue responses. Mammary and endocrine morphology and systemic hormone balance will be assessed after exposure to chemical carcinogen. The relation between carcinogen-induced changes in morphology of the mammary gland and endocrine organs and the circulating levels of estrogen, progesterone, growth hormone and prolactin will be described. Mammary morphologic responses to various hormone combinations will be compared in vitro between control tissues and tissues from perinatally hormone-treated animals. Permanent cellular alterations in mammary tissues will be identified by alterations in differentiative response to hormones in organ culture. BIBLIOGRAPHIC REFERENCES: Warner, M. R.: 1976 Age incidence and site distribution of mammary dysplasias in young beagle bitches. J. Nat. Cancer Inst. 57:57-61. Warner, M. R.: 1976 Effects of perinatal estrogen on mouse mammary pretreatment requirement for in vitro lobular differentiation. Tissue Culture Association - 27th Annual Meeting (Abstract) In Vitro 12:330.